hdu1509 (Windows Message queue) Priority queue

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Problem Descriptionmessage queue is the basic fundamental of Windows system. For each process, the system maintains a message queue. If something happens to this process, such as mouse click, text change, the system would add a message to the queue. Meanwhile, the process would do a loop for getting message from the queue according to the priority value if it's not empt Y. Note the less priority value means the higher priority. In this problem, you is asked to simulate the message queue for putting messages to and getting message from the message Queue.
Inputthere ' s only one test case in the input. Each command, "GET" or "PUT", which means getting message or putting message. If the command is "PUT", there ' re one string means the message name and both integer means the parameter and priority Follo Wed by. There'll is at the most 60000 command. Note that one message can appear twice or more and if the messages has the same priority, the one comes first would be pro Cessed first. (i.e., FIFO for the same priority.) Process to the End-of-file.
Outputfor each "GET" command, the output of the command getting from the message queue with the name and parameter on one line. If There's no message in the queue, output "EMPTY queue!". There ' s no output for "PUT" command.
Sample Input

Getput MSG1 5PUT msg2 4GETGETGET

Sample Output

EMPTY queue!msg2 10MSG1 10EMPTY queue!

Test instructions

Operate according to the operation instructions, that is, the team, or the queue. And at the time of the team. Be careful. Ensure that the priority level is low first, if the priority is the same. Just get out first. From the topic is very easy to see the priority queue to do, just the Java package has a Priorityqueue class, is a ready-made priority queue.

Problem-solving process: First, according to test instructions, can build a message class, where the bread contains mesg some information, mainly include, priority and enter the team's serial number (this serial number must be required, that is, the first few into the team, the following will know). Then you can get an answer based on the instructions step by steps.

Attention:

1, the Priorityqueue class and the ordinary queue the most basic difference is more than a comparison device. Under normal circumstances, all of them by implementing the comparator interface to write a comparison device, in the new priority queue when the device is dropped in the OK,

In the construction method, there isPriorityQueue(int initialCapacity,Comparator<?

super E> comparator)

creates one with the specified initial capacity PriorityQueue and sorts the elements according to the specified comparison.

2, although the priority queue is placed in the element, it will be compared with the comparison in the corresponding position. But as for how the interior is relatively, how to put it. I haven't gone into it yet, but I know it here. Although the problem is that it is stored by priority and then stored in the order of the queue, it sounds like only a consideration.

Priority sort. Subjectively you will think that just the same priority, that is, compare returns 0. It will be placed at the same priority level. But advanced comes the element behind. In fact otherwise, this is not the case, it is necessary to pass the serial number of the team to achieve the desired goal.

Code implementation:

Import Java.util.comparator;import Java.util.priorityqueue;import Java.util.scanner;public class P1509 {public static void Main (string[] args) {Scanner sc=new Scanner (system.in); Priorityqueue<message> priorityque=new priorityqueue<message> (6000,new MesCmp ());//priority Queue Message messg;/ /MESSG class int Count=0;while (Sc.hasnext ()) {String operate=sc.next (); if (Operate.charat (0) = = ' G ') {//Outbound if ( Priorityque.isempty ()) {System.out.println ("EMPTY queue!");} Else{system.out.println (Priorityque.poll ());}} else{//Queue messg=new Message (Sc.next (), Sc.nextint (), Sc.nextint (), count++);p Riorityque.add (MESSG);}}} Class message{string Name;int value;int priority;int id;public Message (String name, int value, int priority,int ID) {this. Name = Name;this.value = Value;this.priority = Priority;this.id = ID;} Public String toString () {return name + "" + Value;}} Class MESCMP implements Comparator<message>{public int Compare (message m1, message m2) {if (m1.priority< m2.priority) {return-1;} else if (m1.priority> m2.priority) {return 1;} else{//This assumes that there is no comparison of the ID, then the order will be wrong if (m1.id<m2.id) {return-1;} else if (m1.id>m2.id) {return 1;} Else{return 0;}}}}

hdu1509 (Windows Message queue) Priority queue